Magnetic freeze-out and impurity band conduction in n-InSb

Abstract

Non-ohmic conduction of n-InSb with different donor concentrations ( N d=2×10 14– 1×10 15 cm −3 ) in perpendicular magnetic fields has been measured at low temperatures, in order to infer the impurity band mobility μ i with the aid of the two-band analysis. The decrease of μ i with increasing magnetic fields has been found to reflect exactly the shrinkage of donor wave functions due to magnetic field and the magnetic-field induced metal–insulator transition is an event in the impurity band. The temperature dependence of μ i in moderate magnetic fields above the transition field B c appears to obey the Mott variable-range hopping law as μ i =μ 0 exp[−(T 0/T) x] with x=1/4.